Vibration sensor mounting structure

Abstract

A vibration sensor mounting structure improves the stability and repeatability of a measured signal generated by a machine vibration sensor. The structure has an outer annular surface that contacts the machine under test and a shallow recess inside the outer annular surface. The recess causes resonant vibrations of the mounting structure to occur at frequencies that are above the intended measurement range of the sensor. The recess also allows the mounting force to be positioned away from the center mounting screw and onto the more stable outer annular surface. With the mounting force away from the center, lateral forces have less effect on the measured signal.

What is claimed is: 
     
       1. A mounting structure for contacting a surface of a machine and holding a vibration sensor in relationship to the machine as vibration of the machine is measured by the vibration sensor, the mounting structure comprising:
 a sensor attachment portion for receiving and securely holding the vibration sensor; 
 a base portion rigidly connected to the sensor attachment portion, the base portion comprising:
 an annular mounting surface configured to contact the surface of the machine, the annular mounting surface having an outer radius R and an inner radius r; and 
 a central recessed surface surrounded by the annular mounting surface, the central recessed surface configured not to contact the surface of the machine, 
 
 
       wherein values of the inner radius r and the outer radius R are selected to have a predetermined effect on a resonant frequency response of the mounting structure, 
       wherein the vibration sensor is for use in measuring vibration of the machine at measurement frequencies within a range of 1 Hz to 10 KHz, 
       wherein the vibration sensor has a mass ranging from about 0.65 pounds to about 0.75 pounds, and 
       wherein the outer radius R ranges from 12.3 mm to 12.5 mm and the inner radius r ranges from 8.9 mm to 9.1 mm. 
     
     
       2. The mounting structure of  claim 1  wherein the values of the inner radius r and the outer radius R are selected to cause the resonant frequency response of the mounting structure to be outside a range of measurement frequencies in which the vibration sensor is used to measure vibration of the machine. 
     
     
       3. The mounting structure of  claim 1  wherein the outer radius R is 12.4 mm and the inner radius r is 9.0 mm. 
     
     
       4. The mounting structure of  claim 1  wherein the sensor attachment portion and the base portion are integrally formed as one continuous structure. 
     
     
       5. The mounting structure of  claim 1  further comprising a central hole through the base portion for receiving a bolt or stud for attaching the mounting structure to the surface of the machine. 
     
     
       6. The mounting structure of  claim 5  wherein the central hole has a radius that is less than the inner radius r of the annular mounting surface. 
     
     
       7. The mounting structure of  claim 1  wherein the annular mounting surface is substantially flat. 
     
     
       8. The mounting structure of  claim 1  wherein the annular mounting surface is defined as a portion of a surface of a toroid. 
     
     
       9. The mounting structure of  claim 1  wherein the central recessed surface is recessed to a depth ranging from 0.2 mm to 0.4 mm in relation to the annular mounting surface. 
     
     
       10. The mounting structure of  claim 1  wherein the central recessed surface is recessed to a depth of 0.3 mm in relation to the annular mounting surface. 
     
     
       11. A mounting structure for contacting a surface of a machine and holding a vibration sensor in relationship to the machine as vibration of the machine is measured by the vibration sensor, the mounting structure comprising:
 a sensor attachment portion for receiving and securely holding the vibration sensor; 
 a base portion rigidly connected to the sensor attachment portion, the base portion comprising:
 an annular mounting surface configured to contact the surface of the machine, the annular mounting surface having an outer radius R and an inner radius r; 
 a central recessed surface surrounded by the annular mounting surface, the central recessed surface recessed to a depth ranging from 0.2 mm to 0.4 mm in relation to the annular mounting surface; and 
 a central hole through the base portion for receiving a bolt or stud for attaching the mounting structure to the surface of the machine, 
 
 
       wherein the value of the inner radius r is selected from a range of 8.9 mm to 9.1 mm and the value of the outer radius R is selected from a range of 12.3 mm to 12.5 mm, thereby causing the resonant frequency response of the mounting structure to be above a range of measurement frequencies in which the vibration sensor is used to measure vibration of the machine. 
     
     
       12. The mounting structure of  claim 11  wherein the inner radius r is greater than or equal to 71% of the outer radius R and less than or equal to 75% of the outer radius R. 
     
     
       13. The mounting structure of  claim 11  wherein the outer radius R is 12.4 mm and the inner radius r is 9.0 mm. 
     
     
       14. The mounting structure of  claim 11  wherein the sensor attachment portion and the base portion are integrally formed as one continuous structure. 
     
     
       15. The mounting structure of  claim 11  wherein the central hole has a radius that is less than the inner radius r of the annular mounting surface. 
     
     
       16. The mounting structure of  claim 11  wherein the annular mounting surface is substantially flat. 
     
     
       17. The mounting structure of  claim 11  wherein the annular mounting surface is defined as a portion of a surface of a toroid. 
     
     
       18. The mounting structure of  claim 11  wherein the central recessed surface is recessed to a depth of 0.3 mm in relation to the annular mounting surface. 
     
     
       19. A mounting structure for contacting a surface of a machine and holding a vibration sensor in relationship to the machine as vibration of the machine is measured by the vibration sensor, the mounting structure comprising:
 a sensor attachment portion for receiving and securely holding the vibration sensor; 
 a base portion rigidly connected to the sensor attachment portion, the base portion comprising:
 an annular mounting surface configured to contact the surface of the machine, the annular mounting surface having an outer radius and an inner radius, wherein the inner radius is greater than or equal to 71% of the outer radius and less than or equal to 75% of the outer radius; and 
 a central recessed surface surrounded by the annular mounting surface, the central recessed surface configured not to contact the surface of the machine. 
 
 
     
     
       20. A mounting structure for contacting a surface of a machine and holding a vibration sensor in relationship to the machine as vibration of the machine is measured by the vibration sensor, the mounting structure comprising:
 a sensor attachment portion for receiving and securely holding the vibration sensor; 
 a base portion rigidly connected to the sensor attachment portion, the base portion comprising:
 an annular mounting surface configured to contact the surface of the machine, the annular mounting surface having an outer radius of 12.4 mm and an inner radius of 9.0 mm; and 
 a central recessed surface surrounded by the annular mounting surface, the central recessed surface configured not to contact the surface of the machine. 
 
 
     
     
       21. A mounting structure for contacting a surface of a machine and holding a vibration sensor in relationship to the machine as vibration of the machine is measured by the vibration sensor, the mounting structure comprising:
 a sensor attachment portion for receiving and securely holding the vibration sensor; 
 a base portion rigidly connected to the sensor attachment portion, the base portion comprising:
 an annular mounting surface configured to contact the surface of the machine, the annular mounting surface having an outer radius and an inner radius; and 
 a central recessed surface surrounded by the annular mounting surface, the central recessed surface configured not to contact the surface of the machine, wherein the central recessed surface is recessed to a depth ranging from 0.2 mm to 0.4 mm in relation to the annular mounting surface, 
 
 
       wherein values of the inner radius and the outer radius are selected to have a predetermined effect on a resonant frequency response of the mounting structure.